Socket head screw



March 26, 1946. D, v sTELLlN SOCKET HEAD SCREW 2 Sheets-Sheet 1 Filed June 16, 1944 r V my m 5 7 .v Z5 m W 0 March 26, 1946. D. v. STELLIN 2,397,216

SOCKET HEAD SCREW Filed June 16, 1944 2 Sheets-Sheet 2 n 1 VENTOR.

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Patented Mar. 26, 1946 UNITED STATES PATE T OFFICE SOCKET HEAD SCREW Domnic V. Stellin, Bronx, N. Y. Application June 16, 1944, Serial No. 540,621

'7 Claims.

addition the work is scratched or defaced and the screw head is burred, so that considerable time is lost in removing the broken screw.

One of the objects of th invention is to eliminate the breaking of screws and the resulting injury and damage. The hexagon type of socket, for example, is very popular but is seldom used in flat head screws due to the fact that the thickness of metal around the socket becomes thinner and weaker a the head tapers inwardly of the screw axis. According to my invention, the socket also is tapered inwardly, in various form as well as the hexagonal, 'so' that the ,metal thickness around the socket remains constant and the liability of breakage is practically eliminated.

Another difficulty with the present socket head screws is that the power screw driver does not readilyenter the socket, since there must be accurate registration of non-circular shapes. Another object of the invention is to overcome this difliculty and is accomplished also by the tapering socket in conjunction with a tapering screw driver. Thus, the screw driver enters the socket quite freely and is gradually seated or registered after entering, thereby avoiding the burring of the screw head top and damaging of the work resulting from initial misalinement.

Still another object of the invention is to eliminate breaking of sharp corners on the screw driver and within the socket. For example, a fingershaped recess presents sharp corner extending into therecess and liable to breakage. According to the invention, breakage is avoided by rounding off such corners. Again, a'triangular ple in th following description and in the accompanying drawings in which:

recess requires sharp cornersv on the tool, and this situation is met by rounding the angles of the triangle and also rounding the edges of the screw driver. With the same object in view. sockets with large internal angles are contemplated, since the corresponding large angles of the screw driver strengthen the sharp corners and protect them from breakage.

The invention is fully disclosed by way of exam- I conventional.

3 which, in this case, is hexagonal in cross sec- Figure l is a plan view of a flat head machine screw; 1

Figure 2 is a plan view of a machine set screw;

Figure 3 is a plan view of another machine set screw;

Figures 4, 5 and 6 are longitudinal sections of the screws shown respectively in Figures 1, 2 and 3;

Figure '7 is a plan view of a set screw;

Figure 8 is a plan view of another flat head machin screw;

Figure 9 is a plan view of still another flat head machine screw;

Figures 10, 11 and 12 are longitudinal sections of the screws shown respectively in Figures '1, 8 and. 9; I

Figure 13 is a plan view of a filister type screw;

Figure 14 is a plan view of another set screw; I

Figure 15 is a plan view of a round head machine screw;

Figures 16, 17 and 18 are longitudinal sections of the screws shown respectively in Figures 13, 14 and 15; Figure 19 is a plan view of a stripper screw; Figure 20 is a plan view of a wood screw; Figures 21 and 22 are longitudinal sections of the screws shown respectively in Figures 19 and Figure 23 is an elevation of a wrench for a socket head cap screw; I

Figure 24 is an elevationof a machine wrench for a socket head screw;

Figure 25 i's a longitudinal section of asocket head cap screw with a difierent shape of socket;

and v Figure 26 is a plan view thereof.

Reference to these views will now be made by use of like characters which are employed to designate corresponding parts throughout.

In Figures 1 and 4 is shown a fiat head machine screw includinga shank I and a downward-,,

1y tapered head 2. The threads, not shown, are In the head is formed a recess tion. Approximately the upper third of the height of the recess is'of uniform dimensions as indicated at 4, while the remainder converges.

downwardly at 5, at an angle of 10 to 15 degrees to the projected wall 4. The upper or outer edge of the recess is preferably bevelled slightly at 6 or turned on a radius.

This construction is similar in its general propcities to the modifications described hereinafter..

The screw driving tool is shaped to fit in the socket or reces 3 and, being smaller at the entering end, is easily received in the wider end of the socket. Due to the taper of both the tool and the socket, the tool seats gradually, without undue clashing of surfaces and burring of th screw. Also. the provision of a tapering socket in a tapering screw head maintains a substantially uniform wall thickness and strength in-the'head. In contradistinction a socket of uniform cross sectional area in a tapering head weakens the head at the bottom of the socket, resulting in breakage of the screw, injury to adjacent workers, damaging of the work and nearby equipment, and loss of time in removing the broken screw, as previously set forth.

The entry of the driving tool is further facilitated by the obtuse internal angles of the hexahedral socket. Where these angles are acute, as in modifications presently to be described, the corners are rounded to eliminate breaking of corresponding tool angles or protruding angles in the socket.

Figures 2 and 5 show a machine set screw having a threaded shank In of uniform diameter. The socket II- therein is triangular in plan section with approximately the upper third of its length being of uniform cross sectional area, at I2, and the remainder tapering slightly inward at I3. A chamfer I4 is formed at the upper edge of the socket, and all angles are rounded at I5.

- Thus, the corresponding angles of the driving tool need not be sharp and breakable.

In the machine set screw 20 shown in Figures 3 and 6, the socket 2I is of a substantially fourleaf clover design. The upper portion 22 tapers inwardly while the lower 25%, approximately, of its length is straight-walled at 23. The upper edge of the socket is chamfered at 24. Sucha design necessarily presents inwardly converging angles or internal angles exceeding 180. The

apices of, such angles would ordinarily be liable to breakage under impact and pressure of the driving tool. In order to eliminate thispossibility, the angles are rounded at 25 both in the socket proper and in the chamfer.

Figures '7 and show a set screw 30 having a socket 3| with four sides 32 that are convex within the socket. The upper portion of the socket tapers inwardly at 33, and the bottom fraction is straight-walled at 34. The corners formed between adjacent sides 32 are rounded at 35 in order not to require a sharp-comered driving tool a previously set forth.

In Figures 8 and 11 is shown a fiat head machine screw having a shank 40 and a tapered head 4|. The socket 42 therein has two parallel edges 43, in any transverse plane, joined by two curved sides 44 concave within the socket. It is evident that this arrangementof fiat andcurved walls eliminates sharp comers between adjacent walls. The height of the socket is divided substantially into thirds, the upper third being of uniform cross sectional area at 45, the middle third tapering inwardly at 46, and the lower third being also of uniform cross section at 41. The upper edge is chamfered at 48.

A similar stepped formation is provided in the nut head machine screw shown in Figures 9 and 12, having a shank 50 and a head 5|. .The cross sectional configuration of the socket 52 is substantially square, with the internal corners rounded at 53. 'The upper edge is chamfered at 54. The upper portion of the socket isof uniform cros section at 55. the middle portion 56 I character.

tapered inwardly, and the bottom portion 51 again of uniform cross section.

Figures 13 and 16 show the invention applied to a filister type screw having a threaded shank 60 and a shouldered head GI. The socket 52 is hexahedral and tapers inwardly along substantially its entire length except for a considerable chamfer 63 at its upperend. As in Figures 1 and 4, the internal angles are obtuse, requiring similar angles on the driving tool. These angles, although converging to sharp apices, are hardly liable to breakage, because of their obtuse Figures 14 and 17 illustrate a set screw I0 having a cross shaped socket II that tapers inwardly and has its upper end chamfered at I2. As in Figures 3 and 6, some of the intemal angles are greater than 180 and present edges projecting into the socket. Such edges are rounded off as indicated by the numeral I3.

In Figures 15 and 18 is shown a round head set screw having a threaded shank I5 and a head I6. The socket 11 therein is of three-fingered formation and presents obtuse internal angles within the socket. These are rounded oif at I8 for the reasons previously set forth. The socket tapers inwardly along nearly its entire length and has a substantial chamfer I9 at its upper end.

Figures 19 and 21 show a stripper screw having a shank 80, a threaded end 8| and a cylindrical head 82. The socket 83 therein is multi-flngered and presents internal obtuse angles which are rounded off at 84 as previously set forth. The

socket tapers inwardly and has its upper end chamfered at 85.

In Figures 20 and 22 is shown a wood screw having a threaded shank and a tapered head 9|. The socket 92 is also m-ulti-fingered, and the obtuse internal angles formed thereby are rounded off at 94. The socket tapers inwardly and is formed with a chamier 95 at its upper end.

A typical machine-operated driver for the screws is shown in Figure 23. It consists of a shank 96 carrying a head 91 shaped to fit in the socket of the particular screw to be driven. The head tapers at 98 and is otherwise shaped to conform to the socket.

- In Figure 24 is shown a hand wrench for a screw having a socket of the finger type. The shank 99 is preferably at a right angle to the head I00. The head tapers at IM to conform to the socket and embodies rounded lugs I02 shaped to fit-in the. aforementioned rounded comers of the socket.

The taper angles of the sockets, although stated cap screw IIO having a head III with a recess 'I I2 therein. The recess is inthe form of a twoblade propeller," having two convexside walls 3' and two shorter concave side walls H4. The comers formed by adjoining walls are rounded at II5 to accommodate a round-cornered driving tool as previously set forth. I The upper edge of the recess H2 is chamfered at I I6, from which approximately half the. depth of the recess is ofuniform cross sectional configuration as shown at I II. The remaining, lower gagement of the driving tool with the screw head.

in driving relation and similarly facilitate disengagement when similar action occurs in all the constructions having curved walls in whole or in part, convex or concave, or a combination thereof.

In all embodiments described herein, the primary purpose is to avoid breaking the screw head or the driver, especially when the screw has been driven home. This purpose is accomplished, for

the most part, by the avoidance of sharp corners in the recesses and the provision of a roundcomered driving tool which rides out of the recess more readily than a sharp-cornered tool from a sharp cornered recess. Again, the provision of large internal angles, or the avoidance of deep radial pockets, in the recess contributes further to the easy seating of the driver and easy automatic withdrawal of the driver from the recess.

In the embodiments having a stepped recess with a straight-walled portion at the bottom, the screw driver makes its driving engagement comparatively quickly. This is for the reason that the driver need not seat fully in the recess before commencing to drive. It commences to drive as soon asit enters the straight-walled portion whether above or below, and then completes the seating movement. A uniformly tapered recess and driving tool on the other hand, do not establish driving relation until the tool has fully seated.

Although specific embodiments of the invention have been illustrated and described, itwill be understood that various alterations in the details of construction may be made without departing from the scope of the invention as indicated by the appended claims.

What I claim is:

1. In a screw, a head formed with a recess having a plurality of symmetrically arranged faces, one end of said recess being of a uniform crosssectional area and co-axial with the screw, and an adjacent portion of said recess tapering inwardly of the screw at an angle of about 5 to the screw axis, said tapering portion being truncated in a plane perpendicular to its axis.

2. In a screw, a head formed with a recess having a plurality of symmetrically arranged faces, the inner end of said recess being of a uniform recess having an intermediate portion with walls cross-sectional area and co-axial with the screw, and an adjacent portion of said recess tapering inwardly of the screw at an angle of about 5 vto the screw axis.

3. In a screw, a head formed with a recess having a plurality of symmetrically arranged faces,

the outer end of said recess being of a uniform cross-sectional area and co-axial with the screw, and an adjacent portion of said recess tapering inwardly of the screw at an angle of about 5 to the screw axis.

4. In a screw, a head formed with a recess having a plurality of symmetrically arranged fades, the end portions of said recess being each. of uniform cross-sectional area and co-axial with the screw, the inner end portion being of smaller cross-sectional area than the outer portion, said recess having an intermediate portion with walls tapering from said outer portion to said inner portion.

5. In a screw, a head formed with a recess having a plurality of symmetrically arranged faces, the end portions of said recess being each of uniform cross-sectional area and co-axial with the screw, the inner end portion being of smaller cross-sectional area than the outer portion, said recess having an intermediate portion with walls tapering from said outer portion to said inner portion, I the corners of said portions being rounded. I

6. In a screw, a head formed with a recess having a plurality of symmetrically arranged faces, the end portions of said recess being each of uniform cross-sectional area and co-axial with the screw, the inner end portion being of smaller cross-sectional area than the outer portion, said recess having an intermediate portion with walls tapering from said outer portion to said inner portion, certain corresponding walls of each of said portions being curved and the remaining walls being plane.

7. ma screw, a head formed with a recess having a plurality of symmetrically arranged faces, the end portions of said recess being each of uniform cross-sectional area and co-axial with the screw, the inner end portion being of smaller cross-sectional area than the outer portion, said tapering from said outer portion to said imier portion at an angle of about 5 to the screw axis.

DOMNIC V. STELIJN. 

